Allergic and irritant reactions to plants and insects

Michael Gochfeld gochfeld at eohsi.rutgers.edu
Tue Jul 31 05:40:07 EDT 2001


The mention of skin rashes and eye irritation from plants and insects is 
not new, but it is obvious that under certain cases these reactions can 
be severe and debilitating. 

Irritant materials are generally "irritating" to a most people with some 
variability in how individuals respond. And these reactions generally 
involve a direct toxic effect on tissues or cells. Thus fiber glass and 
sandpaper are irritating and there are many plant chemicals that are 
irritants as well. 

Allergic responses tend to be more idiosyncratic. Some are common (for 
example 5-20% of a population might become sensitized to nickel or 
mango) while others are rare (less than 1% of exposed people become 
sensitized). And the reaction involves the immune system. 

But, there may be source variability as well as receptor variability. 
Milkweeds differ in their alkaloid composition, accounting for the 
different palatability of the Monarch's that grow on them. Perhaps they 
vary as well in their ability to inflict painful responses. 

I regularly pull up Common Milkweed by hand and am exposed to the milky 
"sap", but I certainly anticipate that if it ever got in my eye it would 
be irritating. 

Another difference is that irritant reactions may occur immediately 
(within seconds or minutes).  Allergic reactions may occur within 
minutes (immediate hypersensitivity) or may take 24-48 hours to develop 
(delayed hypersensitivity).  These represent different immune 
mechanisms. 

It would be interesting to know how many people response adversely and 
details about the nature of the response (localized at the point of 
contact or general; symmetrical or asymmetrical). 

Michael Gochfeld


 
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